Chemical vapor deposition reactor

ABSTRACT

A chemical vapor deposition reactor for depositing a thin film on at least a substrate through a reaction between a vertical input reagent gas flow and the at least a substrate is provided, in which a vertical output reagent gas flow is produced after the reaction. The reactor includes a vertical tube, at least a reaction chamber located inside the vertical tube, an input flow baffle located on the at least a reaction chamber, and at least a gas exit installed on the at least a reaction chamber for exhausting the vertical input reagent gas flow and the vertical output reagent gas flow. In addition, the substrate is located at the bottom of the at least a reaction chamber. The provided reactors allow the achievement of more efficient heating process, lower gas consumption and higher growth uniformity than the conventional reactors.

FIELD OF THE INVENTION

[0001] This invention relates to a reactor, and more particularly to a chemical vapor deposition reactor.

BACKGROUND OF THE INVENTION

[0002] Chemical vapor deposition is a thin film deposition technique about using a method of depositing a solid product onto a chip surface from reactants by a chemical reaction in a reactor. The reactants are usually gas reactants. After decades of developments, the chemical vapor deposition has become the most important and the main deposition method in the semiconductor manufacturing process for depositing a thin film on the semiconductor elements, such as conductors, semiconductors, and dielectric materials.

[0003] The key equipment of the facilities for chemical vapor deposition is a reactor, where is the place for deposing a thin film. However, the designs for chemical vapor deposition reactors are different from one another according to their application scopes. A Hydrogen Vapor Phase Epitaxy reactor, HVPE reactor, is one of the popular chemical vapor decomposition reactors.

[0004] The conventional HVPE reactors for growth of compound semiconductors of IV and III-V groups of periodical table and their alloys are well-known in the industry. These reactors can be divided into three main groups according to their geometrical features. The three main groups are respectively HVPE reactors with horizontal geometry of gas flow (HG HVPE reactors), HVPE reactors with vertical geometry of gas flow (VG HVPE reactors), and HVPE reactors with close shower head (SH HVPE reactors).

[0005] Please refer to FIG. 1, which shows a structural diagram of a prior HG HVPE reactor. As shown in FIG. 1, the HG HVPE reactor includes a horizontal tube 11, a horizontal reagent gas flow 12, a substrate 13, and a gas heater 14. A hydride thin film is deposited on the substrate 13 through a reaction of the horizontal reagent gas flow 12 in the HG HVPE reactor. The relevant structures and features of HG HVPE reactors are disclosed in U.S. Pat. Nos. 6,176,925, 6,177,292, 6,179,913 and 6,350,666.

[0006] The disadvantages of above-mentioned HG HVPE reactors include: 1. It's difficult to obtain a high efficiency of gas utilization and high growth uniformity of the thin film simultaneously. 2. A big gas heater 14 with high power consumption is necessary to avoid the temperature gradients inside the horizontal tube 11. 3. Because it is difficult to obtain the temperature difference between the reactor inside walls and the substrate 13, a deposition material will be deposited onto the reactor inside walls. 4. Because of the high relaxation times of temperature and gas flow rate changes, a Quantum Well structure, QW structure, is unable to be grown. 5. Because the symmetry of the reactor is low, it is difficult to control and model the growth processes of the thin film.

[0007] Please refer to FIG. 2, which shows a structural diagram of a prior VG HVPE reactor. As shown in FIG. 2, the VG HVPE reactor includes a vertical tube 21, a vertical reagent gas flow 22, a substrate 23, and a gas heater 24. A hydride thin film is deposited on the substrate 23 through a reaction of the vertical reagent gas flow 22 in the VG HVPE reactor. The relevant structures and features of VG HVPE reactors are disclosed in U.S. Pat. Nos. 5,980,632 and 6,086,673.

[0008] The disadvantages of above-mentioned VG HVPE reactors include: 1. The growth uniformity of the thin film is not yet ideal enough. 2. A big gas heater 24 with high power consumption is still necessary to avoid the temperature gradients inside the vertical tube 21. 3. Because it is still difficult to obtain the temperature difference between the reactor inside walls and the substrate 23, a deposition material will be deposited onto the reactor inside walls. 4. Because of the high relaxation times of temperature and gas flow rate changes, a Quantum Well structure, QW structure, is either unable to be grown.

[0009] Please refer to FIG. 3, which shows a structural diagram of a prior SH HVPE reactor. As shown in FIG. 3, the SH HVPE reactor includes a horizontal tube 31, a vertical reagent gas flow 32, a substrate 33, a gas heater 34, and a shower-type head 35. A hydride thin film is deposited on the substrate 33 through a reaction of the vertical reagent gas flow 32 in the SH HVPE reactor. The SH HVPE reactor further includes a horizontal gas flow 36 as a buffer gas. The relevant structures and features of SH HVPE reactors are disclosed in U.S. Pat. No. 4,574,093.

[0010] The disadvantages of above-mentioned SH HVPE reactors include: 1. The sprinkle nozzle 35 is a non-technological design, so that the sprinkle nozzle 35 is difficult to be fabricated practically. 2. Because it is difficult to obtain the temperature difference between the reactor inside walls and the substrate 33, deposition materials are deposited onto the reactor inside walls and the sprinkle nozzle 35.

[0011] As above-mentioned, a HVPE reactor with the abilities of high efficiency of gas utilization and high growth uniformity of thin film, which avoids the erroneous deposition, is worthy for the relevant industries.

[0012] Because of the technical defects described above, the applicant keeps on carving unflaggingly to develop a “CHEMICAL VAPOR DEPOSITION REACTOR” through wholehearted experience and research.

SUMMARY OF THE INVENTION

[0013] It is an object of the present invention to provide a HVPE reactor with the advantages of being able to obtain high efficiencies of gas utilization and high growth uniformity of the thin film simultaneously.

[0014] It is another object of the present invention to provide a HVPE reactor with opposite direction flow geometry and extended diffusion layer. Also, a quantum well structure can be formed on a semiconductor material in the HVPE reactor.

[0015] It is the other object of the present invention to provide a HVPE reactor with a small volume and low power consumption.

[0016] In accordance with one aspect of the present invention, a reactor is provided for depositing a thin film on at least a substrate through a reaction between a vertical input reagent gas flow and the at least a substrate. A vertical output reagent gas flow is produced after the reaction. The reactor includes a vertical tube, at least a reaction chamber located inside the vertical tube, an input flow baffle located on the at least a reaction chamber, and at least a gas exit installed on the at least a reaction chamber for exhausting the vertical input reagent gas flow and the vertical output reagent gas flow. In addition, the substrate is located at the bottom of the at least a reaction chamber.

[0017] Preferably, the reactor is a hydride vapor deposition reactor.

[0018] Preferably, the input flow baffle is located on a top of the at least a reaction chamber.

[0019] Preferably, the at least a gas exit is installed on a side wall of the at least a reaction chamber.

[0020] Preferably, the reactor is made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics.

[0021] Preferably, the vertical input reagent gas flow is a mixture of HCl, GaCl, NH₃, and Ar gases.

[0022] Preferably, the substrate is a sapphire substrate.

[0023] Preferably, the thin film is one compound semiconductor selected from a group consisting of IV group and their alloys, III-V groups and their alloys, and GaN.

[0024] Preferably, the vertical output reagent gas flow is a mixture of HCl, GaCl, Cl₂, NH₃, and H₂ gases.

[0025] Preferably, the reactor further has an extended diffusion layer formed from a bottom of the reaction chamber to the gas exit for increasing a utility rate of the vertical input reagent gas flow and a deposition unity.

[0026] Preferably, the vertical tube includes a first gas heater and a second gas heater.

[0027] Preferably, the first gas heater is one of an external side wall gas heater and an internal side wall gas heater.

[0028] Preferably, the second gas heater controls a temperature difference between the substrate and walls of the reactor.

[0029] Preferably, the second gas heater is an external bottom gas heater.

[0030] Preferably, the second gas heater includes an input gas tube and a heater.

[0031] Preferably, the reaction chamber is a cylindrical chamber.

[0032] Preferably, the reactor further includes an extended diffusion layer for transport of the vertical input reagent gas flow to the substrate.

[0033] In accordance with another aspect of the present invention, a hydride vapor deposition reactor is provided for depositing a thin film on a substrate through a reaction between a vertical input reagent gas flow and the substrate. A vertical output reagent gas flow is produced after the reaction. The reactor includes a vertical tube with two side wall gas heaters and a bottom gas heater, a plurality of first input flow baffles located inside the vertical tube for extending routes of the vertical input reagent gas flow and the vertical output reagent gas flow, a reaction chamber located inside the vertical tube and upon the substrate, at least a second input flow baffle located on a top of the reaction chamber, and at least a gas exit installed on a side wall of the reaction chamber for exhausting the vertical input reagent gas flow and the vertical output reagent gas flow.

[0034] Preferably, the thin film is one compound semiconductor selected form a group consisting of III-V groups and their alloys, IV groups and their alloys, and GaN.

[0035] Preferably, the two side wall gas heaters are a first gas heater and a second gas heater respectively located on external side walls of the vertical tube.

[0036] Preferably, the vertical tube further includes a Ga vessel.

[0037] Preferably, the reactor further includes an extended diffusion layer formed from a bottom of the reaction chamber to the gas exit for increasing a utility rate of the vertical input reagent gas flow and a deposition unity.

[0038] Preferably, the plural first input flow baffles are located above the reaction chamber.

[0039] For understanding this application further, some figures and detailed illustrations are shown as follows:

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 shows a structural diagram of a prior HG HVPE reactor;

[0041]FIG. 2 shows a structural diagram of a prior VG HVPE reactor;

[0042]FIG. 3 shows a structural diagram of a prior SH HVPE reactor;

[0043]FIG. 4 shows a structural diagram of the HVPE reactor according to a preferred embodiment I of the present invention;

[0044]FIG. 5 shows a structural diagram of the HVPE reactor according to a preferred embodiment II of the present invention;

[0045]FIG. 6 shows a structural diagram of the HVPE reactor according to a preferred embodiment III of the present invention;

[0046]FIG. 7 shows a structural diagram of the HVPE reactor according to a preferred embodiment IV of the present invention;

[0047]FIG. 8 shows a structural diagram of the HVPE reactor according to a preferred embodiment V of the present invention; and

[0048]FIG. 9 shows a structural diagram of the HVPE reactor according to a preferred embodiment VI of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0049] The present invention provides HVPE reactors with opposite direction flow geometries and extended diffusion layers. And, a quantum well structure can be formed on a semiconductor material in the HVPE reactor.

[0050] Please refer to FIG. 4, which shows a structural diagram of a HVPE reactor according to the preferred embodiment I of the present invention. As shown in FIG. 4, the HVPE reactor includes a vertical tube 41, a first gas heater 45, a second gas heater 46, a reaction chamber 47, at least an input flow diaphragm 49, and at least a gas exist slit 410. The reaction chamber 47 includes a container space 48. And, a substrate 43 for being deposited thereon is positioned at the bottom of the container space 48.

[0051] The first gas heater 45 is positioned on the external side wall of the vertical tube 41, and the second gas heater 46 is positioned at the external bottom wall of the vertical tube 41. The reaction chamber 47 is located inside the vertical tube 41 and is a cylindrical reaction chamber. The input flow diaphragm 49 is positioned on the top of the reaction chamber 47, and the at least a gas exist slit 410 is located on the internal side wall of the reaction chamber 47 with a particular distance from the substrate 43. An extended diffusion layer 411 is formed between the height of the at least a gas exist slit 410 and the bottom of the reaction chamber 47. The reaction chamber 47 is made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics. The substrate 43 is a sapphire substrate.

[0052] The HVPE reactor of the preferred embodiment I is used for depositing the thin film 412 on the substrate 43 by a reaction between the vertical input reagent gas flow 42 and the substrate 43. And, an opposite-direction vertical output reagent gas flow 44 is produced after the reaction. The vertical input reagent gas flow 42 and the vertical output reagent gas flow 44 can be exhausted through the gas exist slit 410.

[0053] The vertical input reagent gas flow 42 is a mixture of HCl, GaCl, NH₃, and Ar gases. The thin film 412 is a compound semiconductor selected from a group consisting of III-V groups and their alloys, IV group and their alloys, and GaN. The vertical output reagent gas flow 44 is a mixture of HCl, GaCl, NH₃, Ar, and H₂ gases. And, the second gas heater 46 is used for controlling the temperature difference between the substrate 43 and the internal side walls of the reactor.

[0054] On the other hand, the substrate 43 is not directly reacted with the vertical input reagent gas flow 42. The reaction is proceeded during the diffusion process of the vertical input reagent gas flow 42 in the extended diffusion layer 411. Meanwhile, the vertical input reagent gas flow 42 is still in a gas state during the diffusion process. Because the second gas heater 46 can be used to control the temperature difference between the internal side walls of the reactor and the substrate 43, no deposition will be formed on the internal side walls of the reactor.

[0055] Therefore, the advantage of the reactor according to the preferred embodiment I is that the first gas heater 45 and the second gas heater 46 are not necessary to be sealed up, because they are not directly exposed to the vertical input reagent gas flow 42 and the vertical output reagent gas flow 44. This reduces the reactor volume effectively.

[0056] Please refer to FIG. 5, which shows a structural diagram of a HVPE reactor according to the preferred embodiment II of the present invention. As shown in FIG. 5, the HVPE reactor includes a vertical tube 51, a first gas heater 55, a second gas heater 56, a reaction chamber 57, at least an input flow diaphragm 59, and at least a gas exist slit 510. The reaction chamber 57 includes a container space 58. And, a substrate 53 for being deposited thereon is positioned at the bottom of the container space 58.

[0057] The first gas heater 55 is positioned on the internal side wall of the vertical tube 51 and upon the input flow diaphragm 59. The second gas heater 56 is positioned at the external bottom of the vertical tube 51. The reaction chamber 57 is located inside the vertical tube 51 and is a cylindrical reaction chamber. The input flow diaphragm 59 is positioned on the top of the reaction chamber 57, and the at least a gas exist slit 510 is located on the internal side wall of the reaction chamber 57 with a particular distance from the substrate 53. An extended diffusion layer 511 is formed from the height of the at least a gas exist slit 510 to the bottom of the reaction chamber 57. The reaction chamber 57 is made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics. The substrate 53 is a sapphire substrate.

[0058] The HVPE reactor of the preferred embodiment II is used for depositing a thin film 512 on the substrate 53 by a reaction between the vertical input reagent gas flow 52 and the substrate 53. And, an opposite-direction vertical output reagent gas flow 54 is produced after the reaction. The vertical input reagent gas flow 52 and the vertical output reagent gas flow 54 can be exhausted through the gas exist slit 510.

[0059] The vertical input reagent gas flow 52 is a mixture of HCl, GaCl, NH₃, and Ar gases. The thin film 512 is a compound semiconductor selected from a group consisting of III-V groups and their alloys, IV group and their alloys, and GaN. The vertical output reagent gas flow 54 is a mixture of HCl, GaCl, NH₃, Ar, and H₂ gases. And, the second gas heater 56 is used for controlling the temperature difference between the substrate 53 and the internal side walls of the reactor.

[0060] On the other hand, the substrate 53 is not directly reacted with the vertical input reagent gas flow 52. The reaction is proceeded during the diffusion process of the vertical input reagent gas flow 52 in the extended diffusion layer 511. Meanwhile, the vertical input reagent gas flow 52 is still in a gas state during the diffusion process. Because the second gas heater 56 can be used to control the temperature difference between the internal side walls of the reactor and the substrate 53, no deposition will be formed on the internal side walls of the reactor.

[0061] The first gas heater 55 is directly exposed to the vertical output reagent gas flow 54, so that the first gas heater 55 of the HVPE reactor of the preferred embodiment II needs to be sealed up. Furthermore, the advantage of the HVPE reactor according to the preferred embodiment II is more sensitive to the temperature change than the HVPE reactor of the preferred embodiment I.

[0062] Please refer to FIG. 6, which shows a structural diagram of a HVPE reactor according to the preferred embodiment III of the present invention. As shown in FIG. 6, the HVPE reactor includes a vertical tube 61, a first gas heater 65, a second gas heater 66, a reaction chamber 67, at least an input flow diaphragm 69, and at least a gas exist slit 610. The reaction chamber 67 includes a container space 68. And, a substrate 63 for being deposited thereon is positioned at the bottom of the container space 68.

[0063] The first gas heater 65 is positioned on the internal side wall of the vertical tube 61 and upon the input flow diaphragm 69. The second gas heater 66 is positioned at the external bottom of the vertical tube 61. The reaction chamber 67 is located inside the vertical tube 61 and is a cylindrical reaction chamber. The input flow diaphragm 69 is positioned on the top of the reaction chamber 67, and the at least a gas exist slit 610 is located on the internal side wall of the reaction chamber 67 with a particular distance from the substrate 63. An extended diffusion layer 611 is formed from the height of the at least a gas exist slit 610 to the bottom of the reaction chamber 67. The reaction chamber 67 is made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics. The substrate 63 is a sapphire substrate.

[0064] Particularly, the second gas heater 66 includes an input gas tube 612 and an internal heater 613. A input reagent gas flow 614 is heated by the internal heater 613 while being flown through the input gas tube 612. An output reagent gas flow 615 is formed after the heated input reagent gas flow 614 is reflected from the bottom of the substrate 63. The input reagent gas flow 614 and the output reagent gas flow 615 are oppositely directed and thermally coupled. Because the temperature of the substrate 63 directly depends on the heated input reagent gas flow 614, the temperature can be changed quickly.

[0065] The HVPE reactor of the preferred embodiment III is used for depositing a thin film 616 on the substrate 63 by a reaction between the vertical input reagent gas flow 62 and the substrate 63. And, an opposite-direction vertical output reagent gas flow 64 is produced after the reaction. The vertical input reagent gas flow 62 and the vertical output reagent gas flow 64 can be exhausted through the gas exist slit 610.

[0066] The vertical input reagent gas flow 62 is a mixture of HCl, GaCl, NH₃, and Ar gases. The thin film 616 is a compound semiconductor selected from a group consisting of III-V groups and their alloys, IV group and their alloys, and GaN. The vertical output reagent gas flow 64 is a mixture of HCl, GaCl, NH₃, Ar, and H₂ gases.

[0067] In the preferred embodiment III, the substrate 63 is not directly reacted with the vertical input reagent gas flow 62. The reaction is proceeded during the diffusion process of the vertical input reagent gas flow 62 in the extended diffusion layer 611. And, the vertical input reagent gas flow 62 is still in a gas state during the diffusion process. The second gas heater 66 is used for controlling the temperature difference between the substrate 63 and the internal side walls of the reactor, so that no deposition will be formed on the internal side walls of the reactor.

[0068] The reactors of the preferred embodiment I, II, and III are used for depositing a thin film on single substrate, so that they are not suitable for mass production. On the other hand, the following reactors of the preferred embodiment IV and V are suitable for mass production of the substrates with a thin film.

[0069] Please refer to FIG. 7, which shows a structural diagram of a HVPE reactor according to the preferred embodiment IV of the present invention. As shown in FIG. 7, the HVPE reactor includes a vertical tube 71, a first gas heater 75, a second gas heater 76, a reaction chamber 77, at least an input flow diaphragm 79, and at least a gas exist slit 710. The reaction chamber 77 includes a container space 78. And, the substrates 73 for being deposited thereon are positioned at the bottom of the container space 78.

[0070] The first gas heater 75 is positioned at the external side wall of the vertical tube 71, and the second gas heater 76 is positioned on the external bottom of the vertical tube 71. The reaction chamber 77 is located inside the vertical tube 71 and is a cylindrical reaction chamber. The input flow diaphragm 79 is positioned on the top of the reaction chamber 77, and the at least a gas exist slit 710 is located on the internal side wall of the reaction chamber 77 with a particular distance from the substrates 73. An extended diffusion layer 711 is formed from the height of the at least a gas exist slit 710 to the bottom of the reaction chamber 77. The reaction chamber 77 is made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics. The substrates 73 are sapphire substrates.

[0071] The HVPE reactor of the preferred embodiment IV is used for depositing the thin film 712 on each of the substrates 73 by reactions between the vertical input reagent gas flow 72 and the substrates 73. And, an opposite-direction vertical output reagent gas flow 74 is produced after each reaction. The vertical input reagent gas flow 72 and the vertical output reagent gas flow 74 can be exhausted through the gas exist slit 710.

[0072] The vertical input reagent gas flow 72 is a mixture of HCl, GaCl, NH₃, and Ar gases. The thin film 712 is a compound semiconductor selected from a group consisting of III-V groups and their alloys, IV group and their alloys, and GaN. The vertical output reagent gas flow 74 is a mixture of HCl, GaCl, NH₃, Ar, and H₂ gases.

[0073] In the preferred embodiment IV, the substrates 73 are not directly reacted with the blowing of the vertical input reagent gas flow 72. The reactions are proceeded during the diffusion process of the vertical input reagent gas flow 72 in the extended diffusion layer 711. And, the vertical input reagent gas flow 72 is still in a gas state during the diffusion process. The second gas heater 76 is used for controlling the temperature difference between the substrates 73 and the internal side walls of the reactor, so that no deposition will be formed on the internal side walls of the reactor.

[0074] Please refer to FIG. 8, which shows a structural diagram of a HVPE reactor according to the preferred embodiment V of the present invention. As shown in FIG. 8, the HVPE reactor includes a vertical tube 81, a plurality of first gas heaters 85, a plurality of second gas heaters 86, a plurality of reaction chambers 87, at least an input flow diaphragm 89, and at least a gas exist slit 810. Each of the reaction chambers 87 includes a container space 88. And, each of the substrates 83 for being deposited thereon is positioned at the bottom of each container space 88.

[0075] The first gas heaters 85 are positioned on the external side walls of the vertical tubes 81 respectively, and the second gas heaters 86 are positioned at the external bottoms of the vertical tubes 81. The reaction chambers 87 are respectively located inside the vertical tubes 81 and are cylindrical reaction chambers. The input flow diaphragm 89 is positioned on a top of the reaction chamber 87, and the gas exist slit 810 is located on the internal side wall of the reaction chamber 87 with a particular distance from the height of the substrate 83. A plurality of extended diffusion layers 811 are respectively formed from the gas exist slits 810 to the bottoms of the reaction chambers 87. The reaction chambers 87 are made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics. The substrates 83 are sapphire substrates.

[0076] The HVPE reactor of the preferred embodiment V is used for respectively depositing the thin film 812 on the substrate 83 by a reaction between the vertical input reagent gas flow 82 and the substrate 83. And, an opposite-direction vertical output reagent gas flow 84 is produced after the reaction. The vertical input reagent gas flow 82 and the vertical output reagent gas flow 84 can be exhausted through the gas exist slit 810.

[0077] The vertical input reagent gas flow 82 is a mixture of HCl, GaCl, NH₃, and Ar gases. The thin film 812 is a compound semiconductor selected from a group consisting of III-V groups and their alloys, IV group and their alloys, and GaN. The vertical output reagent gas flow 84 is a mixture of HCl, GaCl, NH₃, Ar, and H₂ gases.

[0078] In the preferred embodiment V, the substrate 83 is not directly reacted with the vertical input reagent gas flow 82. The reaction is proceeded during the diffusion process of the vertical input reagent gas flow 82 in the extended diffusion layer 811. And, the vertical input reagent gas flow 82 is still in a gas state during the diffusion process. The second gas heater 86 is used for controlling the temperature difference between the substrate 83 and the internal side walls of the reactor, so that no deposition will be formed on the internal side walls of the reactor.

[0079] The reactors of the preferred embodiment I, II, III, IV, and V are the main designs of the HVPE reactors in the present invention. The following reactor of the preferred embodiment VI is an extended reactor of the preferred embodiment I.

[0080] Please refer to FIG. 9, which shows a structural diagram of a HVPE reactor according to the preferred embodiment VI of the present invention. As shown in FIG. 9, the HVPE reactor includes a vertical tube 91, a first gas heater 95, a second gas heater 914, a third gas heater 96, a reaction chamber 97, at least a second input flow diaphragm 99, a plurality of first input flow diaphragms 912, at least a gas exist slit 910, a Ga vessel 913, and a water cooled flange 915. The reaction chamber 97 includes a container space 98. And, the substrate 93 for being deposited thereon is positioned at the bottom of the container space 98.

[0081] The first gas heater 95 is positioned on one external side wall of the vertical tube 91, the second gas heater 914 is positioned on another external side wall of the vertical tube 91, and the third gas heater 96 is positioned at the external bottom of the vertical tube 91. The reaction chamber 97 is located inside the vertical tube 91 and is a cylindrical reaction chamber. The second input flow diaphragm 99 is positioned on the top of the reaction chamber 97 and upon the first input flow diaphragms 912 positioned inside the vertical tube 91. The gas exist slit 910 is located on the internal side wall of the reaction chamber 97 with a particular distance from the substrate 93. An extended diffusion layer 911 is formed from the height of the gas exist slit 910 to the bottom of the reaction chamber 97. The reaction chamber 97 is made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics. The substrate 93 is a sapphire substrate.

[0082] The HVPE reactor of the preferred embodiment VI is used for depositing the thin film 916 on the substrate 93 by a reaction between the vertical input reagent gas flow 92 and the substrate 93. And, an opposite-direction vertical output reagent gas flow 94 is produced after the reaction. The vertical input reagent gas flow 92 and the vertical output reagent gas flow 94 can be exhausted through the gas exist slit 910.

[0083] The vertical input reagent gas flow 92 is a mixture of HCl, GaCl, NH₃, and Ar gases. The thin film 916 is a compound semiconductor selected from a group consisting of III-V groups and their alloys, IV group and their alloys, and GaN. The vertical output reagent gas flow 94 is a mixture of HCl, GaCl, NH₃, Ar, and H₂ gases. The first input flow diaphragm 912 is for extending the flowing routes of the vertical input reagent gas flow 92 and the vertical output reagent gas flow 94, and enhancing the thermal interaction between the reagent gas flow 92 and 94. Furthermore, the volume of the reactor can be effectively reduced by the design of first input flow diaphragm 912.

[0084] In the preferred embodiment VI, the substrate 93 is not directly reacted with the vertical input reagent gas flow 92. The reaction is proceeded during the diffusion process of the vertical input reagent gas flow 92 in the extended diffusion layer 911. And, the vertical input reagent gas flow 92 is still in a gas state during the diffusion process. The third gas heater 96 is used for controlling the temperature difference between the substrate 93 and the internal side walls of the reactor, so that no deposition will be formed on the internal side walls of the reactor.

[0085] As above-mentioned, the features of the HVPE reactors provided by the present invention include:

[0086] 1. The reactor has a design of a vertical input reagent gas flow and a vertical output reagent gas flow being oppositely directed and thermally coupled. The design makes the effect of the gas heating improved effectively and allows a reactor with a smaller volume. Besides, with the ability of quick responding to the changes of the temperature and the reagent gas flowing rate, the HVPE reactors are potentially suitable for the growth of quantum well structures.

[0087] 2. With the design of an extended diffusion layer, the input reagent gas flow can be reacted with the substrate in a gas state during the diffusion process, so that it is possible to enhance the utilization efficiency of the reagents and obtain a good growth uniformity of the thin film.

[0088] 3. The external bottom gas heater of the HVPE reactors according to the present invention allows the control of the temperature difference between the substrate and the internal side wall of the reactor, so that no deposition is formed on the internal side walls of the reactor.

[0089] 4. The reaction chamber of the present invention is a cylindrical chamber with high symmetry, so that it is easy to control the model the deposition processes.

[0090] Thus, the advantages of the HVPE reactors provided by the present invention can be summarized as follows:

[0091] 1. Good deposition uniformity.

[0092] 2. High efficiency of gas reagent utilization.

[0093] 3. Compact design.

[0094] 4. Easily controlling and modeling the deposition processes due to the high symmetry.

[0095] 5. Possibility of using low power heater.

[0096] 6. Possibility of growing a QW structure.

[0097] 7. Possibility of suppressing the deposition on the reactor walls.

[0098] While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures. 

What is claimed is:
 1. A reactor for depositing a thin film on at least a substrate through a reaction between a vertical input reagent gas flow and said at least a substrate, wherein a vertical output reagent gas flow is produced after said reaction, comprising: a vertical tube; at least a reaction chamber located inside said vertical tube, wherein said substrate is located at the bottom of said at least a reaction chamber; an input flow baffle located on said at least a reaction chamber; and at least a gas exit installed on said at least a reaction chamber for exhausting said vertical input reagent gas flow and said vertical output reagent gas flow.
 2. The reactor as claimed in claim 1, wherein said reactor is a hydride vapor deposition reactor.
 3. The reactor as claimed in claim 1, wherein said input flow baffle is located on a top of said at least a reaction chamber.
 4. The reactor as claimed in claim 1, wherein said at least a gas exit is installed on a side wall of said at least a reaction chamber.
 5. The reactor as claimed in claim 1, wherein said reactor is made of a material selected from a group consisting of steel, quartz, sapphire, and ceramics.
 6. The reactor as claimed in claim 1, wherein said vertical input reagent gas flow is a mixture of HCl, GaCl, NH₃, and Ar gases.
 7. The reactor as claimed in claim 1, wherein said substrate is a sapphire substrate.
 8. The reactor as claimed in claim 1, wherein said thin film is one compound semiconductor selected from a group consisting of IV group and their alloys, III-V groups and their alloys, and GaN.
 9. The reactor as claimed in claim 1, wherein said vertical output reagent gas flow is a mixture of HCl, GaCl, Cl₂, NH₃, and H₂ gases.
 10. The reactor as claimed in claim 1 further comprising an extended diffusion layer formed from a bottom of said reaction chamber to said gas exit for increasing a utility rate of said vertical input reagent gas flow and a deposition unity.
 11. The reactor as claimed in claim 1, wherein said vertical tube comprises a first gas heater and a second gas heater.
 12. The reactor as claimed in claim 11, wherein said first gas heater is one of an external side wall gas heater and an internal side wall gas heater.
 13. The reactor as claimed in claim 11, wherein said second gas heater controls a temperature difference between said substrate and walls of said reactor.
 14. The reactor as claimed in claim 11, wherein said second gas heater is an external bottom gas heater.
 15. The reactor as claimed in claim 11, wherein said second gas heater comprises an input gas tube and a heater.
 16. The reactor as claimed in claim 1, wherein said reaction chamber is a cylindrical chamber.
 17. The reactor as claimed in claim 1 further comprising an extended diffusion layer for transport of said vertical input reagent gas flow to said substrate.
 18. A hydride vapor deposition reactor for depositing a thin film on a substrate through a reaction between a vertical input reagent gas flow and said substrate, wherein a vertical output reagent gas flow is produced after said reaction, comprising: a vertical tube with two side wall gas heaters and a bottom gas heater; a plurality of first input flow baffles located inside said vertical tube for extending routes of said vertical input reagent gas flow and said vertical output reagent gas flow; a reaction chamber located inside said vertical tube and upon said substrate; at least a second input flow baffle located on a top of said reaction chamber; and at least a gas exit installed on a side wall of said reaction chamber for exhausting said vertical input reagent gas flow and said vertical output reagent gas flow.
 19. The reactor as claimed in claim 18, wherein said thin film is one compound semiconductor selected form a group consisting of III-V groups and their alloys, IV groups and their alloys, and GaN.
 20. The reactor as claimed in claim 18, wherein said two side wall gas heaters are a first gas heater and a second gas heater respectively located on external side walls of said vertical tube.
 21. The reactor as claimed in claim 18, wherein said vertical tube further comprises a Ga vessel.
 22. The reactor as claimed in claim 18 further comprising an extended diffusion layer formed from a bottom of said reaction chamber to said gas exit for increasing a utility rate of said vertical input reagent gas flow and a deposition unity.
 23. The reactor as claimed in claim 18, wherein said first input flow baffles are located above said reaction chamber. 